Indicator-gear for pressure-engines



(No Model.)

P. D. HART. INDICATOR GEAR FOR PRESSURE ENGINES.

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FREDERICK D. HART, OF BROOKLYN, NEIV YORK.

INDICATOR-GEAR FOR PRESSURE-ENGINES.

SPECIFICATION forming part of Letters Patent No. 433,939, dated August 12, 1890.

Application filed January 18, 1890. Serial No, 337,372. (No model.)

To aZZ whom it may concern:

Be it known that I, FREDERICK D. HART, a citizen of the United States, residing in Brooklyn, in the county of Kings and State of New York, have invented a certain new and useful Improvement in Indicator-Gears for Pressure-Engines, of which the following is a specification.

To measure at any time with accuracy the power developed by a steam, hydraulic, or other pressure engine wherein the agent used imparts a reciprocating motion to a piston within a closed chamber, an instrument termed an indicator is usually employed to trace for each circuit of the engine the outline of an inclosed figure or indicator diagram the area of which is a definite measure of the quantity sought. The outline is the path of a point to which two rectilineal motions are given-one proportionate to the variation in pressure acting within the chamber, and the other normal to the first, proportionate to the movement and speed of the piston. To illustrate, fora reciprocating double-acting steam-engine the indicator generally used consists of a small cylinder containing a steam-tight piston, which on one side bears againsta resistance-spring and is moved by steam from the engine-cylinder, freely admitted on the other side. Attached to the indicator-piston is a pencil, which traces the diagram on the surface of a small drum that, by a suitable reducing apparatus connected to the cross-head or other part of the engine having like motion, is partially rotated back and forth under the pencil during each engine-circuit. This rotation is caused by a non-elastic string, which, wound one or two times about the drum, when pulled, revolves it in one direction. As the tension on the string is released a coiled spring attached to the drum rotates it in the contrary direction. To

provide a simple and durable apparatus or specification are these drawings. Figure 1 is a side elevation of the indicator-gear in position; Fig. 2, a side elevation in'detail of that portion of the indicator-gear constituting my invention; Fig. 3, an end elevation and section of the bracket and its connections, and Fig. 4 a plan and section of a pulley forming part of the gear.

The shaft B, placed with its axis parallel to the line of movement of the engine cross head A, is supported at one end on its journal b in the fixed bush II, which is forced into the hole a of the engine-frame A, and near the other end on its journal 12 in the adjustable bush I, which rests in a hole through the bracket D, which is secured to the engine-frame A; by the bolt E. These bushes are made of brass or other suitable material for shaft-bearing. The shaft is free to rotate on its journals, but prevented from moving endwise by its shoulder b, which is closely against a corresponding shoulder h of the bush II, and by its shoulder 12', which is closely against the inner square end of the bush I.

In case of the wear of either shoulders or bush they are again brought into proper contact by means of the nuts J J, which traverse the threads 1' i of the adjustable bush and permit it to be moved sidewise relatively to the shaft in the bracket D. The shaft extends beyond the bearing b", and on this end carries the pulley K, which b the nut O is held against the shoulder b and is kept from ro-- tating independently of the shaft by the key L. In the groove it, around the outer edge of this pulley, the cord 3 from the indicatordrum S is wound. Its end is confined by passing it through a short hole outward from one side of the groove, knotting it and drawing the knot into the larger hole It.

Secured to the cross-head A by the bolts G, through the slotted holes g in its base f, is the movable bracket F, at the outer end of which is the arm f. The lower part of the arm is bored out to receive the shaft B. Normally from the hole therefor and extending outward to the upper end of the arm is the cylindrical hole f into which on the threads 0 is screwed "the cap 0, with its flat-faced shoulder 0 closely against the similar surface in motion.

at the outer end of the arm. In the chamber thus formed between the shaft and cap is the cylindrical latch P and the helical spring Q, which surrounds the latch and is confined, somewhat compressed between the latchshoulder p and the inner end of the cap. The holes g in the base f of the movable bracket are slotted, as shown, to permit adjustment in position of the latter relatively to the crosshead and transverse to its path, as the crosshead and its lower guide may wear.

Along the outer surface of the shaft B is the helical V-shaped groove 7), in depth reaching nearly to the surfaces of the journals 11 b and extending the full length between the shoulders I) Z). At the inner end of the latch P is the lug or wedge p, shaped to fit, but reaching not quite to the bottom of the groove. The outer end of the latch extends through and beyond the cap 0, and carries on the pin N the hand-lever or trip M, formed as shown. At its free end is the rounded handle m, and at the other end are the two jaws m, one on each side of the latch. These jaws are cams of the Same outline. Their outer surfaces m bear, under the tension of the spring Q, against or slide upon the two fiat surfaces 0 one on each side of the center lug 0 of the cap. This lug is also inclosed by the jaws, and thereby rotation of the latch and trip is prevented. It will be seen that these moving parts are so arranged relatively to each other that when the trip-handle is thrown upward the wedge enters into and engages with the helical groove, and when thrown downward the wedge is withdrawn from the groove.

The shaft B is in length greater than the stroke of the cross-head or other reciprocating partof the engine to which the movable bracket F is attached, somewhat more than the width of this bracket, which traverses the shaft at each stroke of the engine when the latter is In operating the gear the trip is thrown up, the latch engages with the helical groove, and the shaft is partially rotated back and forth as the bracket moves to and fro upon it.

The inclination of the helical groove Z) and the diameter of the pulley K together are such that when the shaft is rotated by and between the limits of movement of the bracket the drum-cord is wound on and unwound from the pulley and the indicator-drum an equal length and sufficient to rotate the latter as required. In constructing several of these gears at one time it will be best to give the helical grooves one inclination and to vary the diameters of the pulleys for engines of different strokes, so that the indicator-drum will have for all an angularmot-ion of the same extent.

By the arrangement described the latch and shaft engage along broad flat surfaces, which, being inclined to each other, are kept by the spring closely in contact, whatever may be their wear. Though in this specification reference has been made to the engineframe as supporting the grooved shaft and to the cross-head as the part to which the movingbracket is attached, in applying the indicator-gear to any particular pressure-engine other points of support and attachment answering the purposes in view as set forth herein, if desirable, may as well be chosen.

Having thus described my invention, I claim I. In an indicator-gear for pressure-engines, the combination, with a reciprocating part of the engine and the grooved shaft, of a bracket connected with the reciprocating part of the engine, a latch carried by the bracket, one end of the same adapted to work in the groove of the shaft, a spring located in a spring-chamher in the bracket and serving to force the latch into the groove, a cap for said chamber and bracket, against which one end of the spring bears, and a trip pivoted to the end of the latch to insert and withdraw the latch from the groove in the shaft, and thus connect and disconnect the gear with and from the moving engine.

2. The combination, with a reciprocating part of an engine, of a helically-grooved shaft, an indicator, connections between the said shaft and indicator, a bracket carried by the said reciprocating part of the engine, a springpressed latch carried by the bracket and having its lower end fitted to the groove of the shaft, and a trip pivoted to the upper end of the latch, substantially as described.

3. In an indicator-gear, the combination, with a helically-grooved shaft and an indicator connected therewith and a movable part of an engine, of the bracket F, adj ustably secured to said movable part and having an opening for the shaft, and a chamber f at an angle thereto, a spring-pressed latch P in said chamber having a lug fitting the groove of the shaft, and the trip M, pivoted on the upper end of the latch, substantially as described.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

FREDERICK D. HART.

WVitnesses:

WM. A. ROSENBAUM, THOMAS K. TRENCHARD.

IIO 

